Process for treating cellulose-containing textiles



. ation in part of my Patented Na. 26, 1946 PROCESS FOR TREATINGCELLULOSE- CONTAINING TEXTILES Ernst Weiss, Wattwil, Switzerland,assignor to Heberlein Patent Corporation,

New York, N. Y.,

a corporation of New York No Drawing. Application January 8, 1944,Serial No. 517,580. In

6 Claims.

This invention relates to processes for treating cellulose-containingtextiles and is a continu- U. S. A. application Ser. No. 459,842 filedSeptember 26, 1942. More particularly the invention provides a processfor rendering such textiles stable as to dimensions and at the same timegiving them a good laundryresisting finish. The process is especiallyuseful in treating fabrics consisting of or containing a substantialpercentage of regenerated cellulose artificial silk fibers such forexample as viscose and cuprammonium silk fibers, including staple fibersthereof and mixtures of such fibers.

It is known that textiles made of natural or regenerated cellulose canbe treated with formaldehyde at high temperatures in the presence ofacid acting catalysts. This manner of treatment brings about mainly areduction of the swelling property of the cellulose and an improvementof t e shrinking resistance whereby these effects withstand manylaunderings. At the same time the high and often undesired stretching ofrayon and staple fiber is reduced which efiect is also permanent, sothat these processes offer interesting possibilities especially for thetreatment of rayon and staple fiber made of regenerated cellulose.

A disadvantage of this shrink-resistant finish is the limp feel or handof the goods which can only be eliminated by a subsequent finish which,however, would not only entail an additional operation but furthermorewould cause difliculties with respect to the stabilizing of fabrics tomaintain their dimensions. A further disadvantage of these processes isthat the resistance to abrasion of the textiles is considerably reducedas a result of the treatment with formaldehyde under the saidconditions.

It has now been found that in both of these respects a considerableimprovement can be obtained if the treatment of the cellulose-containingtextiles is effected with formaldehyde solutions having a formaldehydecontent of less than but more than about 2%, in the presence of acidacting catalysts, at temperatures between about '70-160 C. and in thepresence of finishing agents having a stiffening or we ghting action andconsisting of ve etable or animal colloids or their colloidalfilm-forming conversion roducts, which are capable of reacting withformaldehyde to form condensation products which either swell only withdifiiculty in water or areinsoluble therein.

By this process, not only is the abrasive re sistance considerablyimproved but also in gen- Switzerland October 20, 1941 eral thewater-absorbing capacity of the fibers is further reduced. Anotheradvantage consists therelnthat at the same time a good laundryresistingfinish is produced on the goods. Furthe re the properties which are dueto the actio of formaldehyde on the cellulose, as for instance theimproved shrink resistance and the reduction of the stretch of textilesmade from regenerated cellulose are maintained to their full extent.This was the more surprising as it was known from practical operationthat the presence of finishing agents, as for instance starch, on thefiber rendered the action of formaldehyde on the cellulose moredifilcult.

Suitable for the treatment are cellulose-containing textiles of anydescription such as fabrics, yarns, spun yarns and fiber material ofnatural or regenerated cellulose either alone or mixed with otherfibers.

As acid catalysts one can use organic or inorganic acids of any kindwhich have a dissociation constant of at least about 10- to about 3x10-and where such quantities are used as will not cause injury to thecellulose by disintegration (split-up of chemical structure); forinstance depending on the strength of the acid, one may use up to 10grams or more per liter of the impregnating liquid. Also acid salts ofsuch acids can be used or salts which, on account of their dissociationin the presence of heat or their reaction with formaldehyde, have anacid reaction; such for instance as ammonium salts. Also mixtures ofvarious catalysts can be used, for instance one may add buffersubstances or substances which have a swelling action on cellulose asfor instance zinc chloride.

The expression acid catalyst will be used herein to cover or define notonlycatalysts which are acids, but also substances which areacidreacting or which liberate acid in solution or when exposed to thereaction conditions herein described.

As finishing agents having a stiffening or weighting action for thecarrying out of the process, there can be used the customary Vegetableor animal colloidal substances or their technically producedderivatives, as for instance, soluble starch, starch of everydescription, carob meal, gum tragacanth, gum arabic, dextrln, sugar andgelatin. It is also possible to add textile finishing agents, as forinstance, softeners. The finishing agents are used in practicaloperation in quantities of for instance a few grams up to 100 r Ygramsand more per liter of impregnation liquid.

For formaldehyde it is most advantageous to use the 40% technical orcommercial formaldehyde solution or compounds which split offformaldehyde during the reaction, such as its polymers orhexamethylenetetramine. Quantitatively, the formaldehyde content of theimpregnating bath should be below 10% but more than about 2%. A higherconcentration causes a higher reaction speed, and furthermore acrease-resistant effect, which is not intended or desired in connectionwith the present invention, since a diminution of the abrasiveresistance is caused thereby.

Preferably the formaldehyde, catalyst and finishing agent are added tothe same impregnating bath and the goods are immersed therein atordinary or elevated temperature. After a thorough soaking the excessliquid is removed, such for instance as by squeezing and the goods arepre-dried at about 60 C. After the pre-drying, which may be carried outat a higher or lower temperature, the actual condensation takes placebetween about 70-160 0., most preferably in a drying chamber or on aperforated drying drum, by strongly agitated air currents. Also otherdrying equipment which assures uniform heat is suitable, such forinstance as drying with infra-red rays.

For the treatment of fabrics it is most important that these are broughtto definite dimensions approximating those as customary in the trade,since the fabrics are to be stabilized or made shrink-proof at thesedimensions, 1. e., fixed to these dimensions. It is therefore essentialthat these dimensions are maintained during the heating or condensationtreatment. For this purpose one can proceed so that the impregnatedfabrics, after squeezing them out, are tensioned and pre-dried on astenter frame to predetermined dimensions, i. e., to the length andwidth desired for the finished product, or suitably tensioned somewhatin excess of these dimensions, and then pre-dried. Thereafter with thefabric at these predetermined dimensions, the conden sation is eifectedas described above. After rinsing the goods they are finished in theusual manner.

Fabrics thus treated will also, after repeated laundering, shrink onlyvery little and have a durable full hand; they retain thesecharacteristics also during further manufacturing manipulations and inthe made up garment. The resistance to abrasion is good and the swellingproperty, 1. e., swelling in water, is very much reduced. For artificialsilk, including spun rayon fabrics, made from regenerated cellulose, thetensile strength of the wet material as well as the boiling fastness areimproved. Simultaneously, the stretching property of these fabrics,which is troublesome during the manufacturing and while wearing thegarment, is considerably reduced.

We have also found that a considerable amelioration especially of theabrasive resistance of the treated goods is obtained, if colloids arenot added to the formaldehyde solution, but are first applied to thegoods and the finished goods are then subjected to the formaldehydetreatment. It was surprising that this manner of proceeding would beeflicient, because it was known, that the formaldehyde treatmentrequires thoroughly cleansed goods, to enable reaction betweenformaldehyde and cellulose.

Thus my process for treating cellulose containing fibers to reduceshrinkage and give a laundry resistant finish comprises, treating thefibers with "col1oids capable, when heated to react with. formaldehydeto render the fibers insoluble or only slightly soluble in water, dryingand subjecting the fibers to a formaldehyde treatment (theformaldehyde'being of the above content in the solution) in presence ofan acid catalyst, having a dissociation constant of at least about 10-to about 3 10- at a temperature of from about 70 C. to 160 C. for asumclent time toproduce said reaction product and another reactionproduct between formaldehyde and cellulose thus giving to the fiberssaid properties of reduced shrinkage and a laundry resistant finish.

The colloids may be applied to the textile materials by means of a sloppadding machine or a padding mangle or e. g. by a starching mangle witha starch-doctor. Filling materials and finishing agents, such assofteners may be added to the colloids." Mostly it is of importance thatthe fabrics are brought to definite dimensions approximating those ascustomary in the trade after impregnation with the formaldehyde solutionby tensioning them on a stenter frame. The fabrics are then dried andcondensed maintaining those dimensions.

The following examples serve to illustrate only some of the manyembodiments of the invention.

Example 1.A cretonne-like fabric, in warp and filling consisting of spunviscose yarn, was cleansed by customary methods, slightly bleached anddried. Thereafter, it was impregnated on 8.

padding machine with a solution containing per liter:

Solubia (soluble starch) gr 100 Formaldehyde 40% commercial cc 100 Zincchloride pulverized gr 20 Potash alum gr 1o Thereupon it was wellsqueezed (wrung out), tensioned in warp and filling directions to 5%below gray dimensions and while at such dimensions pre-dried at atemperature of 70 C. Thereupon the goods were exposed in a heatingchamber for 2 minutes to a temperature of 130 C., acidified with verydilute acetic acid, thoroughly washed, and tensioned in length and widthto 6% below the gray dimensions and dried.

The fabric is considerably stiffened, and even after repeated launderingthe stiffening is not materially reduced and the tendency of the goodsto shrink is very slight. The resistance to abrasion is 62% higher thanfor similar goods analogously treated, but without the addition ofSolubia to the formaldehyde. By reason of the addition of soluble starchthe swelling property of the fiber material was further dimenished, asis proven by the following figures. The water absorption, in percent,based on the water absorption by similar goods which were only subjectedto a preliminary cleaning, is as follows:

Per cent Fabrics treated according to the above example 58 Fabricstreated analogously, but without the addition of Solubia 73 Thedetermination of the water absorption was carried out by the centrifugemethod.

Example 2.Mercerized, bleached cotton marquislette was impregnated on apadding machine wit Wheat starch kits 5 Formaldehyde 40% com litres 15Aluminium rhodanide solution 17 B.. do 4 Water, sufllcient to make up to..do.. 100

In making up the impregnating solution the starch was made into a pastewith a part of the water by strong stirring at boiling temperature,

cooled off and then mixed in with the other components.

The goods after being well squeezed out were pre-dried at 60 C. whilemaintaining strong length and width tension therein; followed by heatingfor 20 minutes at 110 C.; thoroughly washed with cold water and soapedfor a short time. The fabric is then dried while tensioned in bothdirections to about 4% below the gray dimensions.

By this treatment a good, materially stiffened marquisette finish isobtained which does not lose its character after laundering, and thetendency of the goods to shrink is very slight. The resistance toabrasion is considerably greater than in the case of goods treatedsimilarly, but without the addition of Wheat starch.

Example 3.Spun rayon gabardine, dyed with dye-stuffs fast against theaction of formaldehyde, was impregnated with a solution preparedaccording to the following directions: A gum tragacanth solution wasdiluted with water with the addition of formaldehyde and hydrochloricacid to twice its original volume. The final solution contains perliter:

Gum tragacanth g 50 Formaldehyde 40% commercial cc 150 Hydrochloric acidconc cc 4 The goods were than tensioned in both directions to about 1%in excess of the commercially customary final dimensions and while sotensloned, dried at 60-70". C., thereupon heated in a heating chamberwithout tension for 8 minutes at 120 C., washed with cold water, passedfor 10 minutes through a warm bath (40 C.) containing 0.1% of acommercial fatty alcohol sulphonate plus 0.05% sodium carbonate andafter again'rinsing with cold water, dried. This drying was carried outon a stenter frame maintaining a slight longitudinal pull whilst in thewidth the goods were tensioned to 6% below the width of the gray goods.

The goods obtained by this treatment have, characteristically, a fulleror more voluminous and firmer hand, the finished effect is not lost bylaundering, and the tendency to shrink is considerably reduced. Theresistance to abrasion is materially improved as compared with similargoods analogously treated with formaldehyde, but without the addition ofgum tragacanth. Also in this instance the swelling properties of thefiber material are further diminished.

Example 4.-A well desized rayon taffeta of copper ammonium silk wastreated with a solution containing per liter:

Gum arabic r" 100 Formaldehyde 40% comm cc 200 Zinc chloride gr 16Acetic acid concentrated cc 2 to goods similarly treated without theaddition of gum arabic is improved by more than 30%.

Example 5.-Viscose voile was passed through an aqueous solutioncontaining:

Per cent Potato starch 4 Formaldehyde 4.8 Soromin BS (a cation activesoftener) 1.0 Ammonium chloride 0.4

' ing the goods were tensioned on a hand stenter dimensions.

frame to about 5% below the gray width and length and dried.

For the preparation of the impregnating fluid the potato starch wasboiled with a part of the water for one hour while stirring vigorously.The paste thus obtained was allowed to cool off and thereupon there werestirred into it the other components such as formaldehyde, Soromin andammonium chloride which were dissolved in the remaining part of thewater.

The viscose voile was considerably stiffened by this treatment. Thefinished effect is quite laundry-proof. The swelling property of thefiber material is reduced to a far-reaching extent, which has anespecially favorable effect on the wet strength.

The resistance to abrasion is 65% of that of the original goods. Asample of the same good-s treated in the same manner, but only with theformaldehyde and the catalyst, shows a resistance to abrasion of only32%.

Example 6.-A dyed lining material of viscose satin was impregnated witha solution having the following composition:

Carob kernel meal 2% aqueous solution cc 500 Formaldehyde 40% commercialcc Tartaric acid gr 6 The goods were squeezed out and then subjected ,toa preliminary drying at 60-65 C. while maintained under a good tensionin warp and filling directions, then calendered under strong pressure ona multi-roller calender, heated for 2 minutes at 140 C., washed wellwith cold water, lightly soaped and again dried under tension.

The goods thus treated attained a firm hand; were more resistant to theaction of moisture and in subsequent use did not materially change theirThe resistance to abrasion of goods thus treated as compared to that ofsimilar goods finished in customary manner (i. e., without anyformaldehyde treatment) is only very slightly decreased from a practicalpoint of view (i. e., only about 2 to 3%) while similar goods treatedaccording to this example but without the addition of the carob kernelmeal, showed a decrease of nearly 50% in the resistance to abrasion.

Example 7.Crpe Georgette, consisting of viscose yarn both in the warpand filling, was desized in the customary manner, boiled, bleached anddried. Thereupon it was impregnated with a solution consisting of:

Gelatin -grams 20 Formaldehyde 40% commercial cc Ammonium sulfate grams8 Water cc 970 The fabric was squeezed out and preliminarily dried at 40to 50 0.; while stretched in the direction of the warp and filling toabout 10% below the gray dimensions. Thereafter the fabric was heatedfor 45 minutes at 120 C., thoroughly rinsed with cold water and lightlysoaped, and finally dried under tension. As compared with the graygoods, the finished goods showed a shrinkage of 12% in length and width.

This treatment imparted to the goods a clear stiffening. Furthermore,they became, more translucent and clearer and obtained thereby acharacter similar to a transparentlike crepe. This effect was not lostafter several launderings and the usual strong tendency of crepe fabricsto shrink was in this instance greatly reduced. The resistance toabrasion of goods thus treated is 86% of that of the original goods, ascompared to 58% for a sample of the same goods treated in the samemanner but without the addition of gelatin.

Example 8.--A cretonne-(linen-)like fabric composed of regeneratedcellulose staple fiber is boiled in the known manner, bleached, driedand v treated with a starch paste of 20 g. potato-starch per kg. on aslop padding machine and dried. The so finished fabric is impregnated onthe padding machine with a solution containing per liter Formaldehydeconc. technical (40%) cc 75 Zinc chloride technical g 15 Potash alum g7.5

squeezed and then predried at a temperature of 70 C. while tensioningthe fabric in both directions (weft and warp) at 4-5% below the originaldimensions. The fabric is then heated in a heating room during 2 minutesat 140 C., acidified with strongly diluted acetic acid, washed out,stretched in length and width at 6% below the original dimensions anddried.

Fabrics so finished are distinctly stiffened. The stiffening resistsrepeated laundering and the tendency of the fabric to shrink onlaundering is considerably reduced. The d'minution of swellingFormaldehyde conc. technical (40%) cc 180 Tartaric acid g 10 Water cc820 and driedat 60-70" C. under remarkable tension in the directions offilling and warp, calendered, heated during 8 minutes at 130 C., washedout with cold water. after treated with 1 g./liter of a known fattyalcohol sulphonate at 30 C. during 10 minutes, rinsed and dried undertension. The fabric acquires a firm hand. It is more resistant to theinfluence of moisture and only slightly changes its dimensions onwearing. The fastness to abrasion of the fabric is improved by about 60%when compared witha fabric, showing about the same diminution ofswelling, but not pretreated with the colloids.

Example 10.A regenerated cellulose staple fiber fabric, colour-printedin the well known manner is impregnated on a two-bowl-padding manglewith g. gelatine per liter and dried on Formaldehyde conc. technical(40%) cc 100 Aluminium chloride cryst g 3 Water cc..- 900 dried at 60 C.under tension in the direction of filling and warp so that the fabric isstretched to 4% below the original gray dimensions and thereupon heatedduring 4 minutes at 140 C., washed well with cold water, lightly soapedand dried again.

The fabric shows a linen-like stiffening and only slightly shrinks onlaundering. The finish resists to repeated laundering and the resistanceto abrasion is the same as the untreatedfabric, whilst a fabric notpretreated with the colloid shows a diminution of the resistance toabrasion of about 60%.

With respect to the carrying out of this process, as a general rule, theamount of the impregnating liquid retained in the fabric after squeezingshould be about 80 to compared to the weight of the dry goods. Also thedrying of the fabric after the impregnation and prior to the bakingshould be uniform.

The products obtained following Examples 1-10 are characterized by theinherent quality of being insoluble but swellable in the usualcuprammonium hydroxide solutions and being recognized by the well knownanalytical methods as cellulose chemically combined with formaldehyde.

As stated above, a crease-resistant effect is not intended or desired tobe'produced by my process and, accordingly, the process is carried outuntil the fibers are proof against shrinkage and discontinued beforethey have been rendered substantially crease-proof and before they showany substantial resistance to swelling in the usual cuprammoniumhydroxide solution. Conditions of time, temperature and concentration ofthe materials used are set forth specifically in Examples 1 to 10 toaccomplish this end.

In the claims, where the expression formaldehyde" is used, it isintended to include polymers of formaldehyde and compounds splitting offformaldehyde. Also. where the expression "colloid is used, it isintended to include vegetable or animal colloids or their conversionproducts suitable as finishing agents and having a stiffening orweighting effect.

It may be mentioned that in most cases it is possible to treat fabricsfinished in accordance with the foregoing examples, by a suitablemechanical shrinking process, for instance by sanforizing" in such a waythat even upon repeated washings, the changes in dimensions do notexceed 1%.

While the invention has been described in detail according to thepreferred manner of carrying out the same, it will be obvious to thoseskilled in the art after understanding the invention, that changes andmodifications may be made therein without departing from the spirit orscope of the invention, and it is intended in the appended claims tocover all such changes and modifications.

Having thus described the invention, what is claimed a new and desiredto be secured by Letters Patent, is:

1. A process for treating cellulose fibres, which comprises,impregnating the fibres with a formaldehyde solution having 8.formaldehyde content of less than 10% but more than about 2% in thepresence of an acid catalyst having a dissociation constant of at least1x10- to about 3X10- and in the presence of an aldehyde-reactive agenting conversion products'capable, when heated with formaldehyde, offorming reaction products insoluble or slightly soluble in water,heating the so-treated fibres at about 70-160 C. until the fibres areproof against shrinkage, and discontinuing the treatment before thefibres have been rendered substantially crease-proof and before theyshow any substantial resistance to swelling in the usual cuprammoniumhydroxide solution.

2. A process for treating a fabric containing cellulose fibres, whichcomprises, impregnating the fabric with a formaldehyde solution having aformaldehyde content of less than 10% but more than about 2% in thepresence of an acid catalyst having a dissociation constant of at least1X 10- to about 3X10 and in the presence of an aldehyde-reactive agentselected from-the group consisting of animal and vegetable colloids andtheir colloidal film-forming conversion products capable, when heatedwith formaldehyde, of forming reaction products insoluble or slightlysoluble in water, removing the excess liquid, ad-

justing the fabric to predetermined dimensions and, with the fabric atapproximately said dimensions, heating the so-treated fabric at about70160 C. until the fabric is proof against shrinkage, and discontinuingthe treatment before the fabric has been rendered substantiallycreaseproof and before it shows any substantial resistance to swellingin the usual cuprammonium hydroxide solution.

3. Cellulose fibers, chemically combined with formaldehyde coated with aformaldehyde starch compound and which are shrink-resistant but have nosubstantial crease-proof character, but showing substantially noresistance to swelling in the usual cuprammonium hydroxide solution.

4. Cellulose fibres combined with formaldehyde coated with reactionproducts of formaldehyde with an aldehyde-reactive agent selected fromthe group consisting of animal and vegetable colloids and theircolloidal film-forming conversion products, said coated fibres beingshrink resistant but having no substantial crease-proof character andshowing substantially no resistance to swell- I iilig in the usualcuprammonium hydroxide solut on.

5. A process for treating fabrics containing cellulose whichcomprises,preliminarily impregnating the fabrics with an aldehyde-reactive agentselected from the group consisting of animal and vegetable colloids andtheir colloidal film-forming conversion products capable when heatedwith formaldehyde of forming reaction products insoluble or slightlysoluble in water, drying the fabric so treated and subjecting the sameto a formaldehyde solution having a formaldehyde content of less than 1but more than about 2% in the presence of an acid catalyst having adissociation constant of at least 1X10- to about 3 l0- heatingtheso-treated fabric at about 70-160 C. until the fabric is proof againstshrinkage, and discontinuing the treatment before the fabric has beenrendered substantially crease-proof and before it shows any substantialresistance to swelling in the usual cuprammonium hydroxide solution.

6. A process for treating fabrics containing cellulose which comprises,preliminarily impregnating the fabrics with an aldehyde-reactive agent Iselected from the group consisting of animal and vegetable colloids andtheir colloidal film-formingconversion products capable when heated withformaldehyde of forming reaction products insoluble or slightly solublein water, drying the fabric so treated and subjecting the same to aformaldehyde solution having a formaldehyde content of less than 10% butmore than about 2% in the presence of an acid catalyst having adissociation constant of at least 1X10.- to about 3x10- removing theexcess liquid. adjusting the fabric to predetermined dimensions and,with the fabric at approximately said dimensions, subjecting it in drycondition to a temperature of from about 70-160 C. until the fabricisproof against shrinkage, and discontinuing the treatment before thefabric has been rendered substantially crease-proof and before it showsany substantial resistance to swelling in the usual cuprammoniumhydroxide solution. A i

' ERNST

